Dell e173fpb - backlight

[yofreke]

so our dell monitor pooped out a while ago, here's what i have done on it so far. Power light was flashing. Bought a replacement kit for 6 of the thingamabobers (black plastic front, metal plate on back, three prongs, labled: Q739, Q740, Q743, Q751, Q759, Q760). Lost interest, regained interest, plugged the monitor in to see where i was, and it started spewing a good amount of smoke. Replaced every one of the thingamabobers. Now it will turn on, and after ~1 second the backlights turn off (it is still on however). Checked all of the capacitors, none of them have bulged caps. Gave it a thorough look over, no visible smoke residue or bad looking solder connections.

Hope that this problem hasn't already been addressed somewhere else, but i didn't see mention of a problem where it had done this. Thanks for any help.

[seanc]

Re: Dell e173fpb - backlight

Resolder all transformer legs!

[sabre504]

Re: Dell e173fpb - backlight

As Seanc said resolder the legs on the underside of the board

[smason]

Re: Dell e173fpb - backlight

Thingamabobers? Seriously?

[yofreke]

Re: Dell e173fpb - backlight

As Seanc said resolder the legs on the underside of the board

Alright, so just remove current solder, take them out, read to them some, put them back in? I will do it, but why?

Thingamabobers? Seriously?

Shh, i'm a visual type of person.

[sabre504]

Re: Dell e173fpb - backlight

You dont have to take them out just clear old solder and put fresh in
these are reknowned for poor solder joints on the transformer legs

[smason]

Re: Dell e173fpb - backlight

<disclaimer> I've had a couple </disclaimer>

I will do it, but why?

I'm tempted to say "because we effing told you" but I'll be nice

In semi-non-technical terms:
A very common failure mode on this model is that there are bad solder joints on the inverter transformers. This causes the controller to drive the transistors harder.

Scotty: "Kiptain, the backlights are nay gettin enough pow'r, I'll tell the trannies to kick it up a wee bit"

Kirk: "Who the eff let trannies on my ship"

Sulu: "Oooh, did someone say trannies??",

Anyway, the c5707s and the Fets of which I canna rememerrrr the parrrt number die (usually shorting oot) and sometimes takes out the picofuse just for grins.

Some folks have replaced the fuse and the bad transistors, only to have the same thing happen again, because they dinna resolder the transforrrrmers.

That's my understanding of the situation filtered through about 3 Crown Royals, and a beer or 2.

[retiredcaps]

Re: Dell e173fpb - backlight

Alright, so just remove current solder, take them out, read to them some, put them back in? I will do it, but why?

Possible technical explanation ...

https://www.badcaps.net/forum/showpo...&postcount=269

[hoadle]

Re: Dell e173fpb - backlight

Some time is ccfl backlight is bad that cost shut off too,

[yofreke]

Re: Dell e173fpb - backlight

<disclaimer> I've had a couple </disclaimer>



I'm tempted to say "because we effing told you" but I'll be nice

In semi-non-technical terms:
A very common failure mode on this model is that there are bad solder joints on the inverter transformers. This causes the controller to drive the transistors harder.

Scotty: "Kiptain, the backlights are nay gettin enough pow'r, I'll tell the trannies to kick it up a wee bit"

Kirk: "Who the eff let trannies on my ship"

Sulu: "Oooh, did someone say trannies??",

Anyway, the c5707s and the Fets of which I canna rememerrrr the parrrt number die (usually shorting oot) and sometimes takes out the picofuse just for grins.

Some folks have replaced the fuse and the bad transistors, only to have the same thing happen again, because they dinna resolder the transforrrrmers.

That's my understanding of the situation filtered through about 3 Crown Royals, and a beer or 2.

So even if the connections look fine, they could actually be bad? Just re-melting the connections won't do (cheap soldering wick is the devil)?

EDIT: Also, which fuses will need checking? I'm too unfamiliar with LCD repair, as this is the first one i'm tackling.

[smason]

Re: Dell e173fpb - backlight

Possible technical explanation ...

https://www.badcaps.net/forum/showpo...&postcount=269

Yeah, that's what I meant to say...

[killian6pk]

Re: Dell e173fpb - backlight

<disclaimer> I've had a couple </disclaimer>



I'm tempted to say "because we effing told you" but I'll be nice

In semi-non-technical terms:
A very common failure mode on this model is that there are bad solder joints on the inverter transformers. This causes the controller to drive the transistors harder.

Scotty: "Kiptain, the backlights are nay gettin enough pow'r, I'll tell the trannies to kick it up a wee bit"

Kirk: "Who the eff let trannies on my ship"

Sulu: "Oooh, did someone say trannies??",

Anyway, the c5707s and the Fets of which I canna rememerrrr the parrrt number die (usually shorting oot) and sometimes takes out the picofuse just for grins.

Some folks have replaced the fuse and the bad transistors, only to have the same thing happen again, because they dinna resolder the transforrrrmers.

That's my understanding of the situation filtered through about 3 Crown Royals, and a beer or 2.

That was absolutely great. Are you available for parties.